We represent events as composed of participants. In Joan was eating lasagna in the lecture hall, for example, this eating event is 'partitioned' into participants, including at least Joan, the lasagna, and the lecture hall. In this dissertation, I address two questions about events and the participants that populate them: first, to what extent do we represent event participants as tokens of abstract roles such as Agent? Second, what is the role of the verb in partitioning events into participants? I address these questions through the case study of instrumental participants, as in Joan was eating lasagna with a fork. In a comparison of the semantic properties of instrumental with and use, I argue that Instrument is not a semantic primitive, but that with and use each encode different instrumental properties. Specifically, with requires that the instrument be part of a minimal instance of an event, whereas use specifies that acting on the instrument satisfies the agent's goals. I then address whether verbs such as slice require that events of this type contain an instrument, and whether this requirement indicates that an instrument is an argument of slice. In a novel experimental task, subjects reported their judgments about verbs and the event participants they require. The results from this experiment suggest that instruments are not arguments, but that properties of verbal meaning bias the agent to be interpreted as having subparts. In a second set of studies, I investigated the cross-linguistic generality of these findings. Although the instrument does not appear to be an argument of slice, there may be languages where a verb with a similar meaning as slice does have an instrument argument. To test this hypothesis, I conducted the judgment study described above with speakers of Spanish and Mandarin. The results were strikingly similar across English, Spanish and Mandarin, suggesting that in this domain, concepts about events correspond to language-specific lexicalizations in uniform ways. These studies converge on the same broad understanding of the nature of the instrumental role: a participant that is an extension of the agent.